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SubjectRe: [irqchip: irq/irqchip-next] irqdomain: Protect the linear revmap with RCU
Hi Marc,

On 7/5/21 11:01 AM, Marc Zyngier wrote:
> Hi Guenter,
> On Mon, 05 Jul 2021 18:23:52 +0100,
> Guenter Roeck <> wrote:
>> Hi,
>> On Fri, Jun 11, 2021 at 01:54:36PM -0000, irqchip-bot for Marc Zyngier wrote:
>>> The following commit has been merged into the irq/irqchip-next branch of irqchip:
>>> Commit-ID: d4a45c68dc81f9117ceaff9f058d5fae674181b9
>>> Gitweb:
>>> Author: Marc Zyngier <>
>>> AuthorDate: Mon, 05 Apr 2021 12:57:27 +01:00
>>> Committer: Marc Zyngier <>
>>> CommitterDate: Thu, 10 Jun 2021 13:09:18 +01:00
>>> irqdomain: Protect the linear revmap with RCU
>>> It is pretty odd that the radix tree uses RCU while the linear
>>> portion doesn't, leading to potential surprises for the users,
>>> depending on how the irqdomain has been created.
>>> Fix this by moving the update of the linear revmap under
>>> the mutex, and the lookup under the RCU read-side lock.
>>> The mutex name is updated to reflect that it doesn't only
>>> cover the radix-tree anymore.
>>> Signed-off-by: Marc Zyngier <>
>> This patch results in various RCU warnings when booting mipsel images
>> in qemu. I can not revert the patch due to subsequent changes, so I
>> don't know if a simple revert fixes the problem. Log messages and
>> bisect log see below.
> Thanks for the heads up. Do you have a config file I can use to
> reproduce this? The QEMU invocation runes would certainly help too.
> It strikes me that in drivers/irqchip/irq-mips-cpu.c,
> plat_irq_dispatch() now uses the irqdomain resolution before
> irq_enter() took place. That's certainly a latent bug. I'll fix that
> regardless, but I'd like to make sure this is what you are seeing too.


config Complete configuration file
defconfig Shortened configuration file
rootfs.cpio root file system (initrd) qemu run script (tested with qemu 4.2.1 and 6.0.0)
vmlinux Kernel image experiencing the problem (v5.13-9883-gaf9efb8b661)

Hope this helps,

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